Halogenated phosphinopyranones as fire-retardant polymer additives



Unitecl States Patent 3,243,4i36 HALGGENATED PHOSPHINOPYRANONES AS FlRE-RETARDANT PGLYMER ADDITEVES Sheldon B. Greenbaum, Tonawanda, N.Y., assignor to Hooker Chemical Corporation, Niagara Falls, N.Y., a corporation of New York No Drawing. Original application Jan. 3, 1962, Ser. No. 164,183, now Patent No. 3,200,131, dated Aug. 10, 1955. Divided and this application Get. 21, 1964, Ser.

11 Claims. c1. zen-45.8

BO E) at RIO O/O wherein R and R, which may be the same or different, are members selected from the group consisting of alkyl, aryl, alkaryl, alkenyl, cycloalkyl and haloalkyl; and X is halogen, preferably chlorine and bromine.

One of the major disadvantages of polymeric materials which has greatly restricted their use in commerce, particularly in the construction and textile fields, is their high degree of flammability. While there are numerous instances of using additives such as inorganic salts or oxides, i.e., antimony, tin, etc., to impart non-flammability or fire retardance to these materials, they usually have several real drawbacks. For example, they frequently are present in such high proportions in the resin that they substantially add to the cost of production. Secondly, the inorganic salts or oxides weaken the tensile and physical characteristics of the resin, and often impart opaqueness to the resin making its use in the decorative arts difficult and impractical. Lastly, many inorganic fire-retardant additives tend to segregate or migrate after polymerization which, again, weakens the strength and appearance of the polymer and restricts its life and use.

While some organic additives have been found to overcome some of these disadvantages, they generally are required to be present in large amounts, thus causing all of the attendant disadvantages of high cost, lowered tensile strength and opacity. As an illustration of this is the dimer C Cl claimed in US. 2,724,730, which has been found to be a commercially valuable fire-retardant .additive. However, the composition is required to be present from twenty to fifty percent by weight, accompanied by about ten to twenty percent by weight of a metallic salt. While the resultant polymers are remarkably fire-retardant or completely non-burning, the polymers were opaque and white in appearance which, of course, limited their usefulness except where pigmentation offered no disadvantage.

Amongst the polymers in which the compounds of the invention are useful are the homopolymers and copolymers of unsaturated aliphatic, cycloaliphatic and aromatic hydrocarbons, such as polyethylene, polypropylene, polybutene, ethylene/ propylene copolymers; copolymers of ethylene or propylene with other olefins; polybutadiene; polymers of butadiene, polyisoprene both natural and syn- 3,243,406 Patented Mar. 29, 1966 ice thetic, polystyrene, polyindene, indene-coumarone resins; polymers of acrylate esters and polymers of methacrylate esters. Acrylate and methacrylate resins such as ethyl acrylate, n-butyl methacrylate, isobutyl methacrylate, ethyl methacrylate, and methyl methacrylate; alkyd resins; cellulose derivatives such as cellulose acetate, cellulose acetate butyrate, cellulose nitrate, ethyl cellulose, hydroxyethyl cellulose, methyl cellulose and sodium carboxymethyl cellulose; epoxy resins; furan resins (furfuryl alcohol or furfural-ketone); hydrocarbon resins from petroleum; isobutylene resins (polyisobutylene); isocyanate resins (polyurethanes); melamine resins such as melamineformaldehyde and melamine-urea-formaldehyde; oleo resins; phenolic resins such as phenolformaldehyde, phenolic-elastomer, phenolic-epoxy, phenolic-polyamide, and phenolic-vinyl acetals; polyamide resins such as polyamides and polyamide-epoxy; polyester resins such as polyesters (unsaturated) and polyester-elastomer and polyisobutylene; resorcinol resins such as resorcinol-fonnaldehyde, resorcinol-furfural, resorcinol-phenol-formaldehyde, resorcinol-polyamide and resorcinol-urea; rubbers such as natural rubber, synthetic polyisoprene, reclaimed rubber, chlorinated rubber, polybutadiene, cyclized rubber, butadieneacrylonitrile rubber, butadiene-styrene rub her, and butyl rubber; neoprene rubber (polychloroprene); polysulfides (Thiokol); styrene resins (polystyrene); terpene resins; urea resins; vinyl resins such as vinyl acetal, vinyl acetate or vinyl alcohol-acetate, vinyl acetate copolymer, vinyl alcohol, vinyl alkyl ether, vinyl methyl ether-maleic anhydride copolymer, vinyl chloride, vinyl butyral, vinyl chloride-acetate copolymer, vinyl pyrrolidone and vinylidene chloride copolymer, polyformaldehyde, bitumens and asphalts.

The compositions of the instant invention can be mixed into the polymer or its monomer precursor by any one of several methods. For example, the additives can be introduced into the polymer, while the latter is dissolved in a suitable solvent, or into the monomer prior to the polymerization or during the polymerization. This procedure is especially useful when it is desired to mix the additives during the polymer manufacturing process. When the polymer is subsequently recovered from the solvent, the additives are intimately mixed with the polymer. Usually, the additives are mixed with the polymer in the molten state at temperatures that can range from the melting point to the decomposition temperature of the polymer. Alternatively, the additives and polymer are dry-blended in the finely divided state so that an intimate mixture is obtained upon subsequent molding or extrusion.

The compositions of this invention are desirably incorporated in polymeric materials in the range from about one to about thirty percent by weight of the polymer composition, preferably from about two to about ten by weight.

The compositions of this invention are prepared by the reaction of a perhalocoumalin (tetrahalo a-pyrone or 3,4,5,6-tetrahalo-2H-2-pyranone are alternative names) with an alkyl, aryl or substituted alkyl or aryl phosphite. The perhalocoumalin is prepared according to Canadian Patent 623,279. By substituted alkyl or aryl is meant alkylaryl, alkenylaryl, cycloalkyl and haloalkyl. The gen eral reaction is shown below as if substitution occurred in the 6-position:

wherein R, R and R", which may be the same or differ- 3 ent, are selected from the group consisting of alkyl, aryl, substituted aryl and substituted alkyl as defined supra; and X is a halogen preferably chlorine or bromine. Examples of phosphites which, however, are not limiting are as follows:

Allyloxymethyl ethylene phosphite Cresyl ethylene phosphite Decyl diphenyl phosphite Decyl ethylene phosphite Decyl octylene phosphite Diallyl phenyl phosphite Dibutyl phenyl phosphite Didecyl phenyl phosphite Di-iso-butyl phenyl phosphite -Di-iso-butyl ethyl phosphite Dimethallyl phenyl phosphite Dioctyl phenyl phosphite Di-n-octyl ethyl phosphite Diphenyl allyl phosphite Diphenyl methyl phosphite Phenyl dodecyl phosphite 'Phenyl hexylene phosphite Phenyl propylene phosphite Tetraphenyl ethylene diphosphite Triallyl phosphite Triamyl phosphite Tributyl phosphite -Tricresyl phosphite Trimethyl phosphite Trioctadecyl phosphite Trioctylphenyl phosphite Trioctyl phosphite Tripropyl phosphite Tris (chloropropyl) phosphite Tris (2,4-dichlorophenyl phosphite Tris 2-ethylhexyl phosphite Tris (2-methoxyethoxyethyl phosphite Tris nonyl phenyl) phosphite Tris 2-phenoxyethyl) phosphite Tristearyl phosphite Tristearyl trithiophosphite Tritetradecyl phosphite -Tritetrahydrofurfury1 phosphite Tritridecyl phosphite Where a cyclic phosphite is one of the reactants, the R"X does not split off, but the halogen is part of one of the residual alkoxy groups. Examples of phosphites of this type and the products obtained are:

R R R R =H, alkyl or alkenyl.

R =alkyl or aryl.

While the structures of these compositions have not been exhaustively investigated, the above given structures appear to be likely.

That this type of compound is formed at all in the inventive process is most surprising in view of the prior art, teaching that lactones react with phosphites to cleave the ring and form open-chain esters of the type 0 ll (RO)z1 -(CH2) x OR without the loss of alkyl halide as in applicants novel process. Thus, based upon the known synthetic art, the products and process of this invention are both novel and unexpected.

The present inventive process has rather wide limits of reaction conditions at which it is operable. For example, while the use of an inert solvent is generally preferable for reasons of smoothness of reaction and good yield, the solvent may be dispensed with at some loss of yield and lengthening of reaction time. By an inert solvent is meant a solvent boiling between thirty-five degrees Centigrade and two hundred degrees centigrade, which does not take part in the reaction, and which is not subject to attack by either reactants. Examples of suitable inert solvents are toluene, the xylenes, benzenes, chloroand nitrobenzenes and the like. The reaction is readily run at temperatures between fifty and two hundred degrees centigrade, preferably at one hundred degrees centigrade to one hundred and fifty degrees centigrade. Lower temperatures, while yielding the desired product, greatly extend the reaction time; while higher temperatures cause decomposition and side-products to be a factor. Ordinarily, atmospheric pressures are utilized, but where subatmospheric equipment is available the reaction may be run under high vacuum.

Thus, the preferred process embodiment of this invention is to react a tetrachloro ot-pyrone with the appropriately substituted phosphite in the presence of an arcmatic or substituted aromatic inert solvent at atmospheric pressures at temperatures ranging from one hundred degrees centigrade to one hundred and fifty degrees centigrade, depending upon the reactants involved for periods of time ranging from one hour to seventy-two hours.

In the course of the reaction of this invention, it is believed that substitution of the phosphorus component occurs in the 6-position of the perhalocoumalin. However, since the structures of the novel. compositions have not been exhaustively investigated, the possibility exists that substitution may occur in the 3-, 4- and 5-positions or that a mixture of the substituted products occurs.

Hence, I do not wish to be bound by the fact that in the examples I have shown the substitution to be in the 6-position.

Example 1Preparation 0f dimezhoxyphosphz 'notrichloro-2H-2-pyran0ne A solution of thirty-two grams of trimethyl phosphite in fifty milliliters of toluene is added drop-wise to a stirred refluxing solution of fifty-eight grams of 3,4,5,6-

'5 tetrachloro-ZH-pyranone (perchlorocoumalin) prepared according to Canadian Patent 623,279, dissolved in one hundred milliliters of toluene. .At the end of six hours of refluxing, an aliquot of'the solution no longer de- 6 Example -3Preparati0n of additional phosphinopyranone compositions Using-therproceduredescribed in Examples .1 and 2,

colo'rizes an iodine in benzene solution, indicating comand Substitutingthe indicated phosphite for thetrimethyl pletion of the reaction. The solution is reduced to dryp p the following compositions are pr pared as ness under vacuum-yielding 88.5 grams of crude'prodshown in Table'II whichfollows.

TABLE II Analysis Example No. Phosphite and weight used Product "Form "Empirical formula. Calcd. Found Cl P 01 P 3 Trisbromopropyl (174 g.)1 [Bis (1-brom0-2-propoxy)] phcsphinotrichloro- Oil C iH Br Ol O P 20.4 5.9 20.8 5.7

2H-2-pyranone. 4 Phenyl ethylene (184 g.) (2-chloroethyloxy)phenoxy phosphinotrichlorodo CmH ChOfl" 34.0 7.4 33.8 7.1

ZH-lpyranone. 5 Trinllyl (48.3 g) Diallyloxyphosphintrichl0ro-2H-2-pyra1 OI1e d0- oiinwoltoir 29.6 8.6 29.9 8.7

1 Substitution is believed to have occurred in the fi-position.

2 (+0.5 g. hydroquinone.) uct. Recrystallization from toluene and, then, dilution with methanol gives colorless crystals, melting at eightyseven to eighty-eight degrees centigrade.

Analysis.Calcd. for C H Cl O P: Cl, 34.6 percent; P, 10.1 percent. Found: Cl, 34.6 percent; P, 10.1 percent.

The compound is believed to be 6-dimethoxyphosphino- 3,4,5-trichloro-2H-2-pyranone.

The utility of the compositions of this invention as fire-retardant additives is established in accordance with standard ASTM D-63556-T test procedures as follows:

In this test, the sample to be tested is positioned horizontally three-eighths of an inch above a wire gauze and ignited for thirty seconds with a Bunsen burner. For samples which burn, the burning rate is determined between marks one and four inches from the end of the specimen. For self-extinguishing materials, the time to self-extinguishment (excluding the ignition period) is reported since the total distance burned is generally arrived at during the ignition period. In the case of self-extinguishing specimens, multiple tests (about four to six) were carried out on a single five-inch bar by repeatedly removing the charred parts of the bar after each determination and retesting the newly exposed section.

TABLE I [Flammability of Polypropylene Containing Various Additives] Percent Percent Seli-extinguish- Burning product of 0 01 ing time rate, inches/ Example 1 (seconds) seconds 1 Not self-extinguishing.

Example 2Preparati0n of [bis (1-chl0r0-2-pr0p0xy)] phosphinotrichl0r0-2H-2-pyran0ne Example 6-Fire retardant tests with styrene monomers Mixtures of styrene monomer and the product of Example 1 are made into castings by polymerization at eighty degrees centigrade in the presence of one percent benzoyl peroxide. The castings are tested for flammability by the method of ASTM D63558T described earlier.

TABLE III [ASTM D-635-58T1 Composition (parts by weight) Results Product of Example 1 Styrene 1 14 Instant extinguishingnon-burning. 19 D0. 1 39 Slow burning. Celluflex FR2 (tris-2,3-dichloropropyl phosphate):

1 19 Slow extinguishing. 1 89 Slow burning.

While my invention has been described with reference to certain specific embodiments, it will be recognized by those skilled in the art that many variations are possible Without departing from the spirit and scope of the invention.

I claim:

1. A fire retardant polymeric composition comprising a polymer and from about one to about thirty percent by weight of the polymer composition of the phosphinopyranone having the structure:

wherein -R and R are independently selected from the group consisting of alkyl, aryl, alkaryl, alkenyl, cycloalkyl and haloalkyl, said substituents containing from 1 to 18 carbon atoms, and X is halogen.

4. The method of claim 3 wherein the phosphinopyranone is dimethoxyphosphino-trichloro-2H-2-pyranone.

5. The composition of claim 1 wherein the polymer is polypropylene.

6. The composition of claim 1 wherein the polymer is polymerized styrene.

7. The composition of claim 1 wherein the halogen is selected from the group consisting of chlorine and bromine.

8. The composition of claim 1 wherein the phosphinopyranone is present in an amount from two to ten percent by weight of the polymer composition.

9. A fire retardant polymeric composition comprising polypropylene and from about one to thirty percent, by weight of the polymer composition, of dimethoxyphosphino-trichloro-2II-2-pyranone.

10. The method of claim 3 wherein the phosphinopyranone is present in an amount from two to ten percent by weight of the polymer composition.

11. The method of claim 3 wherein the halogen is selected from the group consisting of chlorine and bromine.

No references cited.

LEON J. BERCOVITZ, Primary Examiner. 

1. A FIRE RETARDANT POLYMERIC COMPOSITION COMPRISING A POLYMER AND FROM ABOUT ONE TO ABOUT THIRTY PERCENT BY WEIGHT OF THE POLYMER COMPOSITION OF THE PHOSPHINOPYRANONE HAVING THE STRUCTURE: 